In an experimental demonstration using a superconducting processor called Zuchongzhi 3.2, China announced a significant breakthrough in quantum error correction, dubbed “quantum supremacy 2.0.”
The Zuchongzhi 3.2 processor successfully operates a surface code logical qubit at a distance of 7.
The noteworthy factor is that as the code distance increases, the logical error rate decreases. This inverse relationship is a critical aspect of China’s latest quantum error correction technique that rivals Google’s previous achievements with its Willow results.
What distinguishes China’s claim is an all-microwave leakage suppression architecture designed to minimize “leakage,” where qubits escape the computational states assumed by error-correcting codes.
Addressing leaks is crucial as it can lead to correlated failures that traditional decoders struggle to handle. This new method makes leakage control a vital design consideration, as previous research has also argued for its importance in keeping surface code cycles clean.
While China’s results aim to match Google’s benchmarks, they do not yet demonstrate the ability to run large calculations on multiple interacting logical qubits.
The transition from a single logical qubit to many poses complex engineering challenges and new failure paths.
IBM’s roadmap emphasizes that scaling up to practical fault suppression systems will require efficient codes and real-time decoding channels.
As the industry embraces the “age of bug fixing,” the focus is shifting to make bug fixing repeatable, automatable, and economically scalable.
As several groups achieve subthreshold behavior, the next challenge is expected to be to efficiently stack logical qubits and maintain manageable error budgets during actual calculations.
